Five Escherichia coli recombinant clones have been identified which react with antibody against Bordetella avium outer membrane proteins and produce 21 kDa, 38 kDa, 40 kDa, 43 kDa, and 48 kDa proteins. In addition, one E. coli clone has been identified which produces a 56 kDa protein which reacts with turkey convalescent sera and three E. coli clones have been identified which react with human convalescent sera from patients infected with Bordetella pertussis. The 21 kDa outer membrane protein gene has been introduced into an avirulent Salmonella typhimurium strain to allow oral immunization of birds and to determine the role of the 21 kDa protein in protection from disease. Spontaneous phase variants of B. avium have been isolated which mimic the phase Ill variants of B. pertussis since they have lost the ability to produce dermonecrotic toxin and four outer membrane proteins. Passage of the B. avium spontaneous phase variants through birds results in reversion of the B.avium phase variants to the wild-type phenotype. Three E. coli clones have been identified which contain cosmid DNA which hybridizes to a radiolabelled oligonucleotide probe for B. avium dermonecrotic toxin. DNA sequence analysis is currently being performed to determine the DNA sequence of the dermonecrotic toxin gene and to deduce the amino acid sequence of B. avium dermonecrotic toxin.